Iraq's Prime Minister Nuri al-Maliki says the northern Kurdish autonomous region’s capital, Irbil, is becoming an operations base for militants in the Islamic State, formerly known as the Islamic State in Iraq and the Levant (ISIL).

In his weekly televised address on July 9, Maliki said: "We will never be silent about Irbil becoming a base for the operations of the Islamic State and Baathists and Al-Qaeda and the terrorists."

Many Sunni Muslims fled to Irbil from the northern Iraqi city of Mosul in June as the militants seized large swathes of territory.

Kurdish militia fighters, known as "peshmerga," also moved into northern Iraqi territory vacated by the Iraqi Army outside of the Kurdish region, including the oil-rich city of Kirkuk.

Iraqi Kurdish leader Masud Barzani has said there is now no going back on autonomous Kurdish rule in Kirkuk.